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Idiopathic Anaphylaxis

Frequently Asked Questions

This document has been developed by ASCIA, the peak professional body of clinical immunology/allergy specialists in Australia and New Zealand. ASCIA information is based on published literature and expert review, is not influenced by commercial organisations and is not intended to replace medical advice. For patient or carer support contact Allergy & Anaphylaxis Australia or Allergy New Zealand.

pdfASCIA PC Idiopathic Anaphylaxis FAQ 2024129.57 KB

Q 1: What is idiopathic anaphylaxis?

Idiopathic anaphylaxis is a rare disorder that results in the same symptoms of anaphylaxis that develop after a severe allergic reaction, however, the ‘trigger’ or reason for the reaction is unknown.

Idiopathic is a medical term that describes a disease or condition that has no known cause.

Anaphylaxis is the most severe type of allergic reaction that usually occurs after exposure to a known allergen, such as food, drug (medication), or insect.

Information about anaphylaxis symptoms is available at

Q 2: How is idiopathic anaphylaxis diagnosed?

Idiopathic anaphylaxis is diagnosed only after your doctor excludes possible causes of reactions, including allergens and diagnoses of other medical conditions that can mimic anaphylaxis.

Your doctor will usually take a detailed medical history and do a physical examination. To assist with the medical history, the ASCIA Anaphylaxis Event Record form can be used to record symptoms, features of reactions and factors that can affect severity of reactions. 

This form is available on the ASCIA website -

Your doctor may sometimes do skin prick testing and allergen challenge tests, or order blood tests for specific IgE antibodies to allergens and serum tryptase.

Information about allergy testing is on the ASCIA website -

Q 3: How is idiopathic anaphylaxis treated?

A reaction due to idiopathic anaphylaxis should always be treated as a medical emergency. Idiopathic anaphylaxis requires immediate treatment with adrenaline (epinephrine), which is injected into the outer mid-thigh muscle.

For people who have frequent reactions (six or more times per year) due to idiopathic anaphylaxis, other preventative treatments may be considered. If the frequency of reactions slows down, regular use of these treatments may be reduced or stopped.

Q 4: How is idiopathic anaphylaxis managed?

People who have frequent reactions because of idiopathic anaphylaxis need ongoing management by a doctor, which should include:

  • Referral to a clinical immunology/allergy specialist -
  • Adrenaline injector prescription (EpiPen® or Anapen®).
  • ASCIA Action Plan for Anaphylaxis to provide guidance on when and how to use adrenaline injectors.
  • Regular follow up visits to a clinical immunology/allergy specialist.
  • Ways to manage stress that may be caused by not being able to know what triggers to avoid.

Q 5: Where can I find more information?

ASCIA anaphylaxis e-training for first aid (community) has been developed for people in the community, who would like to know how to recognise and treat anaphylaxis in an emergency.

ASCIA Anaphylaxis e-training, including short refresher courses, are available and are available free of charge at 

© ASCIA 2024

Content updated March 2024

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